Process for preparing tetrahydropyrimidines

ABSTRACT

Substituted 2, 3, 4, 5-tetrahydropyridimines (THP) ##STR1## are prepared as follows: (1) The reaction of a carbonyl compound (ketone or aldehyde) with (NH 3  or NH 4  OH) and a sulfur-containing catalyst. 
     (2) The reaction of an α, β-unsaturated ketone and a carbonyl compound and NH 3  (or NH 4  OH) without a catalyst. 
     (3) Reaction of an α, β-unsaturated ketone, a 1-amino-alcohol and NH 3  (or NH 4  OH) without a catalyst. 
     The compositions of this invention react with carbon disulfide to form xanthates, can be isomerized, converted to pyridines, etc. 
     Thp and derivatives of this invention are useful as biocides, anti-oxidants, oxygen scavengers, corrosion inhibitors, etc.

This is a continuation of application Ser. No. 292,494, filed Sept. 27,1972, now U.S. No. 4,085,104.

This invention relates to tetrahydropyrimidines (THP), to thepreparation thereof with or without novel catalysts; uses thereof; andto derivatives thereof.

THP is prepared by the following procedures:

I

Reaction of a carbonyl compound (aldehyde or ketone) with ammoniaaccording to the general reaction ##STR2##

II

Reaction of an α, β unsaturated ketone with ammonia and a carbonylcompound (aldehyde or ketone) according to the general reaction ##STR3##

III

Reaction of an unsaturated carbonyl compound (aldehyde or ketone) with a1-aminoalcohol and ammonia according to the general reaction ##STR4##

R₁, R₂, R₃, R₄, R₅ and R₆, which may be the same or different, arehydrogen or substituted group such as alkyl, aryl, cycloalkyl, alkaryl,aralkyl, heterocyclic, substituted derivatives thereof, etc. In additionR groups may be joined in a cyclic configuration which makes the THPstructure a part of the substituted group.

Alkyl includes methyl, ethyl, propyl, butyl, amyl, hexyl, heptyl, octyl,nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl,hexadecyl, heptadecyl, octadecyl, escosyl, docosyl, etc. for examplehaving about 1-25 or more carbons such as from about 1-18 carbons, butpreferably about 1-12 carbons. The term "alkyl" also includes isomers ofthe straight chain where branching occurs.

Cycloalkyl includes cyclopentyl, cyclohexyl, etc. and derivativesthereof such as alkyl cyclohexyl, dialkyl-cyclohexyl, etc.

Aryl, alkaryl and aralkyl include phenyl, alkylphenyl, polyalkylphenyl,chlorophenyl, alkoxyphenyl, naphthyl, alkylnaphthyl, etc., benzyl,substituted benzyl, etc.

The joining of the R groups into a ring structure include thosestructures derived from reactants of the general formula

     (CH.sub.2).sub.n C = O

such as cyclohexanone, cyclopentanone, substituted derivatives thereofsuch as alkyl-cyclohexanone, dialkyl-cyclohexanone.

In general, the catalyst employed herein is a sulfur or asulfur-containing compound. The preferred catalyst is carbon disulfideor the reaction product of CS₂ with an amine to yield an xanthate of thegeneral formula ##STR5## particularly as a salt thereof.

The groups substituted on the nitrogen of the xanthate can vary widelyfor example, alkyl, cycloalkyl, aryl, alkaryl, aralkyl, heterocyclic,etc.

The salt moiety can also vary widely for example alkali metal Na, K, Li,etc., alkali earth, Ca, etc., metal, NH₄, amine, etc.

In the preferred embodiment, CS₂ forms an xanthate inner salt with thetetrahydropyrimidines of this invention such as ##STR6## represents thetetrahydropyrimidine ring having a charged amino group for example##STR7##

The catalyst is employed in a concentration of at least about 0.05 molepercent of the reactants, such as from about 0.05-3.0 mole percent, forexample from about 0.1 to 2.0 mole percent, but preferably from about0.3 to 0.5 mole percent. Larger amounts can be employed, if desired, butthere is generally no advantage in doing so.

In general, the reaction, which is mildly exothermic, is carried out atambient temperatures. Although elevated temperatures can be employed,the reaction is generally carried out at room temperature. Althoughelevated pressures can be employed such as from 0-100 psi, the reactioncan be carried out at atmospheric pressure.

The following equations illustrate the preparation of derivatives of thecompositions of this invention:

The substituted 2, 3, 4, 5 tetrahydropyrimidines of this invention areuseful as intermediate for the preparation of N-dithiocarboxylates.Reaction of the substituted 2, 3, 4, 5 tetrahydropyrimidines with carbondisulfide yielded 1:1 adducts. ##STR8##

These adducts are efficient corrosion inhibitors in acid systems.

2. The tetrahydropyrimidinines can be isomerized from 2, 3, 4, 5 to 1,4, 5, 6 tetrahydropyrimidines ##STR9##

In this reaction it is required that R₆ by hydrogen. These are useful ascorrosion inhibitors.

3. The tetrahydropyrimidines can be converted to substituted pyridines.##STR10## For this reaction, the 2 position contains at least 1 hydrogenand one of the groups attached to carbon 4 has at least a methylenegroup. These are useful as bactericides.

The following examples are presented for purpose of illustration and notof limitation.

EXAMPLE 1 4.4.6 - Trimethyl - 2,3,4,5 - tetrahydropyrimidine

A sample of 392 g. of mesityloxide and 800 cc. of 28% aq. ammoniumhydroxide were stirred in a closed reaction vessel for 3 hours. Themixture was allowed to stand for 15 hours at ambient temperature. To thesolution was added over a 1/2 hour period 300 cc. of an aq. 37% solutionof formaldehyde. The temperature of the reaction mixture rose to 64° C.during the addition. After the addition was completed the mixture wasstirred for 3 hours. Distillation of the reaction product yielded 419 g.(84% of theory) of 4.4.6 - trimethyl - 2,3,4,5 tetrahydropyrimidine as acolorless liquid; b₁₅ 62-65° C.; infrared spectrum, 3.08 m μ, weak(N--H) and 6.02 m μ, strong (C═N); nuclear magnetic resonance spectrum,τ in ppm, no solvent; 5.62 multiplet 2H; 8.14 multiplet + singlet 5H;9.02 singlet 6H; and 7.72 singlet 1H.

Anal. Calc.ed for C₇ H₁₄ N₂ : N, 22.22. Found: N, 21.89.

EXAMPLE 2 2.4.4.6 - Tetramethyl - 2,3,4,5 - tetrahydropyrimidine

In a manner as described in example 1, a sample of 98 g. ofmesityloxide; 200 cc. of 28% aq. ammonium hydroxide; and 50 g. ofacetaldehyde yielded 120.5 g. (86% of theory) of 2.4.4.6 -tetramethyl -2,3,4,5 tetrahydropyrimidine as a colorless liquid; b₁₅ 68-72° C.;infrared spectrum 3.06 m μ weak (N--H) and 6.02 m μ strong (C--N);nuclear magnetic resonance spectrum, τ in ppm, no solvent; 5.68multiplet 1H; 8.15 singlet 3H, 8.20 singlet 2H; 8.77 doublet 3H; 8.93singlet 3H; 9.04 singlet 3H; and 8.41 singlet 1H.

Anal. Calc.ed for C₈ H₁₆ N₂ : N, 20.00. Found: N, 19.89.

EXAMPLE 3 2 - n - Propyl - 4.4.6 - trimethyl - 2,3,4,5 -tetrahydropyrimidine

In a 1 pint pressure reactor was placed 98 g. of mesityloxide and 72 g.of butyraldehyde. Over a 5 hour period a sample of 50.6 g. of ammoniagas was introduced at such a rate that the pressure did not rise above56 psi, After the addition was completed, stirring was continued for 17more hours. The reaction product was dissolved in benzene and theaqueous layer, 34 cc. was separated. The benzene layer was evaporatedunder diminished pressure to yield 178.9 g. of an oil. Distillation ofthe oil under diminished pressure yielded 141 g. (84% of theory) of2-n-propyl-4.4.6 - trimethyl -2,3,4,5 - tetrahydropyrimidine, b₂₀ 78-90°C.; infrared spectrum 3.06 m μ weak (N--H) and 6.01 m μ strong (C═N)

Anal. Calc.ed for C₁₀ H₂₀ N₂ : N, 16.65. Found: N, 16.53.

In a fashion as described in example 3, the following 2-substituted4.4.6 -trimethyl - 2,3,4,5 tetrahydropyrimidines listed in Table I wereprepared from mesityloxide, ammonia gas and an aldehyde.

                                      Table I                                     __________________________________________________________________________    2-Substituted - 4.4.6 - trimethyl - 2,3,4,5 - tetrahydropyrimidines from      mesityloxide, ammonia                                                         gas and an aldehyde                                                           Ex- Mesityl-        Alde-    Reaction                                                                           Maxi- 2-substi-                                                                           Yield                           ample                                                                             oxide           hyde                                                                              Ammonia                                                                            time mum pres-                                                                           ent in                                                                              of                              no. grams                                                                              Aldehyde   grams                                                                             grams                                                                              hours                                                                              sure psi                                                                            Product                                                                             theory                          __________________________________________________________________________    4   98   n-heptaldehyde                                                                           114 44   21   60    n-hexyl                                                                             90                              5   98   2-ethylbutyraldehyde                                                                     100 49   20   55    3-n-pentyl                                                                          90                              6   98   benzaldehyde                                                                             106 47   21   60    phenyl                                                                              96                              7   98   2-ethylhexanal                                                                           128 43   24   65    3-n-heptyl                                                                          88                              8   98   nonylaldehyde                                                                            142 44   24   65    n-octyl                                                                             88                              __________________________________________________________________________

EXAMPLE 9 2.4.4.6 - Tetramethyl - 2,3,4,5 - tetrahydropyrimidine

A sample of 98 grams of mesityloxide and 100 cc. of 28% ammoniumhydroxide were stirred for 18 hours. To the mixture was added 61 gramsof 1-amino-ethanol (acetaldehyde-ammonia) and the mixture was heated to50° C. After all the solid was dissolved, the mixture was allowed tocool to room temperature. Distillation of the product yielded 128 g.(91% of theory) of 2.4.4.6-tetramethyl - 2,3,4,5-tetrahydropyrimidineidentical to the product described in example 2.

EXAMPLE 10 2.2.4.4.6 - Pentamethyl - 2,3,4,5 - tetrahydropyrimidine

In a pressure reactor was placed a mixture of 196 grams of mesityloxideand 137 grams of acetone. Over a 5 hour period 88 grams of ammonia gaswas introduced at such a rate that the autogeneous pressure did notexceed 70 psi. After the addition was completed, the mixture was stirredfor 18 more hours. The resulting reaction product was distilled underdiminished pressure and the product b₂₀ 63-66° C., 265 g. (86% oftheory) of 2.2.4.4.6 - pentamethyl - 2,3,4,5 - tetrahydropyrimidine wascollected; infrared spectrum 3.06 m μ weak (N--H) and 6.02 m μ strong(C--N); nuclear magnetic resonance spectrum τ in ppm, no solvent, 8.12singlet and 8.16 singlet 5H; 8.72 singlet 6H; and 8.96 singlet 6H.

Anal. Calc.ed for C₉ H₁₈ N₂ : N, 18.18. Found: N, ;b 17.97.

As described in example 10, the following 2.2 disubstituted 4.4.6trimethyl - 2,3,4,5 tetrahydropyrimidines, listed in Table II wereprepared from mesityloxide, ammonia gas and a ketone.

                                      Table II                                    __________________________________________________________________________    2.2.-Disubstituted 4.4.6 - trimethyl - 2,3,4,5 - tetrahydro-                  pyrimidines from mesityloxide, ammonia gas a ketone.                             Mesi-         Am- 2.2  boil-                                                                              Ni-    %                                          tyl-      Ke- mon-                                                                              disub-                                                                             ing  tro-   Yield                                   Ex.                                                                              oxide     tone                                                                              ia  stitu-                                                                             point                                                                              gen                                                                              Anal.                                                                             of                                      No.                                                                              grams                                                                             Ketone                                                                              grams                                                                             grams                                                                             ents ° C.                                                                        Cal.                                                                             Found                                                                             theory                                  __________________________________________________________________________    11 98  methylethyl                                                                         72  34  methyl                                                                             b.sub.0.8 =                                                ketone        ethyl                                                                              38-40                                                                              16.65                                                                            16.50                                                                             84                                      12 83  cyclo-                                                                              83  51  penta-                                                                             b.sub.1.0 =                                                hexanone      methy-                                                                             78-80                                                                              14.43                                                                            14.33                                                                             84                                                           lene                                                     13 98  4-methyl-                                                                           112 44  5'methyl                                                                           b.sub.20 =                                                 cyclohex-     penta-                                                                             115-121                                                                            13.46                                                                            13.51                                                                             86                                             amine         methy-                                                                        lene                                                     __________________________________________________________________________

EXAMPLE 14 2.2 Pentamethylene - 4.4.6 - trimethyl - 2,3,4,5 -tetrahydropyrimidine

A mixture of 98 grams of mesityloxide; 98 grams of cyclohexanone, 100grams of methanol and 200 cc. of 28% aq. ammonium hydroxide was stirredfor 19 hours at ambient temperature. The mixture was evaporated underdiminished pressure and the resulting 178 grams of product distilledunder diminished pressure to yield 164 grams (84.5% of theory) of2.2-pentamethylene - 4.4.6 -trimethyl- 2,3,4,5 - tetrahydropyrimidineidentical to the product described in example 12; infrared spectrum,3.04 m μ N--H (weak) and 6.02 m μ C═N (strong); nuclear magneticresonance spectrum; τ in ppm, no solvent; 8.12 singlet 3H; 8.18 singlet2H; 8.47 broad singlet 10H; and 8.97 singlet 6H.

Anal. Calc.ed for C₁₂ H₂₂ N₂ : N, 14.43. Found: N, 14.30.

EXAMPLE 152.4-Dipentamethylene-5,6-tetramethylene-2,3,4,5-tetrahydropyrimidine

To a stirred mixture of 98 grams of cyclohexanone and 93 grams of 28%aq. ammonium hydroxide was added 0.7 cc. of carbon disulfide. Themixture was stirred for 15 more minutes and an additional 0.7 cc. ofcarbondisulfide was added. Stirring was continued for 16 more hours. Themixture was evaporated under diminished pressure and the residuedistilled from solid potassium hydroxide to yield 73 grams (80% oftheory) of2.4-dipentamethylene-5,6-tetramethylene-2,3,4,5-tetrahydropyrimidine asa viscous liquid b₀.8 = 186°-188° C., which slowly solidified uponstanding; infrared spectrum 3.02 m μ weak (N--H) and 6.02 m μ strong(C═N).

Anal. Calc.ed for C₁₈ H₃₀ N₂ : N, 10.20. Found: N, 9.88.

As described in example 15,2.4-Dipentamethylene-5,6-tetramethylene-2,3,4,5-tetrahydropyrimidine wasproduced from cyclohexanone, aq. 28% ammonium hydroxide and carbondisulfide as the catalyst, in varied ratios of reactants. The resultsare collected in Table III.

                  Table III                                                       ______________________________________                                        Formation of 2.4 - Dipentamethylene - 5.6 - tetramethylene -                  2,3,4,5 - tetrahydropyrimidine from cyclohexanone,                            28% aq. ammonium hydroxide and carbon disulfide                                              28% aq.                                                             Cyclohex- Ammonium  Carbon         % Yield                               Ex.  anone     hydroxide disulfide                                                                             Reaction                                                                             of                                    No.  grams     grams     grams   time-hrs.                                                                            theory                                ______________________________________                                        16   49        72        --      18      6                                    17   49        20        0.6     18     53                                    18   49        30        1.2     18     66                                    19   49        40        1.2     18     76                                    20   49        36        1.2     18     76                                    21   49        45        0.8     18     78                                    22   49        20        0.6 + 0.6*                                                                            18     80                                    23   49        72        0.4 + 0.3*                                                                            18     81                                    ______________________________________                                         *Catalyst added in two portions at 15 minutes interval.                  

EXAMPLE 24 Trimethyl 2.4-Dipentamethylene-5,6-tetramethylene-2,3,4,5tetrahydropyrimidine

In a pressure reactor was placed 112 grams of 3-methylcyclohexanone and2 grams of carbon disulfide. To the mixture was added over a 4 hourperiod 14 grams of ammonia gas. After the addition was completed themixture was stirred for 18 more hours at ambient temperature. Theaqueous phase which separated, 17.8 cc., was removed and the productdistilled over potassium hydroxide under diminished pressure. Thetrimethyl2.4-dipentamethylene-5.6-tetramethylene-2,3,4,5-tetrahydropyrimidine wascollected as 76.5 g. (73% of theory) of a very viscous liquid.

EXAMPLE 25 Carbon disulfide adduct of2.4-Dipentamethylene-5.6-tetramethylene-2,3,4,5-tetrahydropyrimidine

A sample of 27.4 grams of2.4-dipentamethylene-5,6-tetramethylene-2,3,4,5-tetrahydropyrimidine wasdissolved in 250 cc. of ether. To the solution was added 10 grams ofcarbon disulfide and the mixture was allowed to stand for 16 hours. Thebright yellow solid which precipitated was filtered off and washed onetime with ether. The product was air dried to yield 34.5 grams (98.5% oftheory) of the carbon disulfide adduct of2.4-dipentamethylene-5.6-tetramethylene 2,3,4,5-tetrahydropyrimidine,m.p. 122°-124° C.

Anal. Calc.ed for C₁₉ H₃₀ N₂ S₂ : N, 8.0 : S, 17.8. Found: N, 8.1 : S,18.3.

EXAMPLE 262.4-Dipentamethylene-5.6-tetramethylene-2,3,4,5-tetrahydropyrimidine

In a pressure reactor was placed 49 grams of cyclohexanone and 1 gram ofcarbon disulfide. Over a 41/2 hour period 7.5 grams of ammonia gas wasintroduced. After the addition was completed the mixture was stirred for3 more hours. The aqueous layer (8.1 cc.) was separated by extraction ofthe product in ether. The ethereal solution was evaporated and theresulting product distilled under diminished pressure to yield 40 grams(87.5% of theory) of2.4-dipentamethylene-5.6-trimethylene-2,3,4,5-tetrahydropyrimidine,identical to product described in example 15.

EXAMPLE 27 Carbon disulfide adduct of2.4-Ditetramethyne-5.6-trimethylene-2,3,4,5-tetrahydropyrimidine

Into a mixture of 84 grams of cyclopentanone, 2 grams of carbondisulfide and 50 grams of methanol was introduced over a 3-1/2 hourperiod 18.2 grams of ammonia gas. After the addition was completed themixture was stirred for 15 more hours at ambient temperature. Thesolvent was removed under diminished pressure and the resulting productwas distilled under diminished pressure. A sample of 18 grams of thedistilled product was dissolved in 100 cc. of ether and 40 grams ofcarbon disulfide was added. The mixture was allowed to stand at roomtemperature for 1 hour and the solid which precipitated was filtered offand washed with ether. The yellow solid was air dried to yield 9.0 gramsof the carbon disulfide adduct of2.4-ditetramethylene-5.6-trimethylene-2,3,4,5-tetrahydropyrimidine, m.p.105°-108° C.

Anal. Calc.ed for C₁₆ H₂₄ N₂ S₂ : N, 9.1; S, 20.8. Found: N, 9.35; S,23.0.

EXAMPLE 28 2.2.4.4.6-Pentamethyl-2,3,4,5-tetrahydropyrimidine

In a pressure reactor was placed 174 grams of acetone and 1.54 grams ofthe carbon disulfide adduct2.4-dipentamethylene-5,6-tetramethylene-2,3,4,5-tetrahydropyrimidine,described in example 25. To the mixture was added 30.4 grams of ammoniagas over a 4 hour period at such a rate that the autogeneous pressuredid not exceed 60 psi. After the addition was completed the mixture wasstirred for 70 more hours. Distillation yielded 90 grams (59% of theory)of 2.2.4.4.6-pentamethyl-2,3,4,5-tetrahydropyrimidine identical to theproduct described in example 10.

In a fashion as described in example 28, 2.2.4.4.6-Pentamethyl2,3,4,5-tetrahydropyrimidine was prepared from acetone, ammonia gas anda catalyst under various conditions. The results are summarized in TableIV.

                                      Table IV                                    __________________________________________________________________________    2.2.4.4.6 Pentamethyl-2,3,4,5 tetrahydropyrimidine from acetone and           ammonia                                                                                    Catalyst                                                                      as pre-    Reaction                                                                           Reaction                                                                           Maximum                                                                             Percent                               Ex.                                                                              Acetone                                                                            Ammonia                                                                            pared in                                                                            Catalyst                                                                           time Tempera-                                                                           pressure                                                                            yield                                 No.                                                                              grams                                                                              grams                                                                              example 28                                                                          grams                                                                              hours                                                                              ture ° C.                                                                   psi   of theory                             __________________________________________________________________________    29 174  50   none  none 21   25-29                                                                              58    5                                     30 174  37   25    0.77 21   26-34                                                                              48    55                                    31 174  50   25    1.54 70   25-35                                                                              44    65                                    32 174  38   25    2.32 21   25-35                                                                              42    66                                    33 174  37   25    3.12 21   28-36                                                                              43    69                                    34 174  38   27    0.77 67   25-33                                                                              48    66                                    __________________________________________________________________________

EXAMPLE 34A 2,4-Di-n-propyl-5-ethyl-2,3,4,5-tetrahydropyrimidine

In a pressure reactor was placed 72 grams of butyraldehyde and 6 gramsof ammonium chloride. To the mixture was added over a half hour period23 grams of ammonia gas. After the addition was completed the mixturewas stirred for 23 more hours at ambient temperature. Ether was added tofacilitate separation of the aqueous phase. The ethereal solution wasevaporated under diminished pressure to yield 64.9 grams (99% of theory)of 2.4-di-n-propyl-5-ethyl-2,3,4,5-tetrahydropyrimidine; infraredspectrum 3.08 m μ (weak) and 6.08 m μ strong absorption.

Anal. Calc.ed for C₁₂ H₂₄ N₂ : N, 14.28. Found: N, 14.05.

EXAMPLE 35 2-Phenyl-4.4.6-trimethyl-3,4,5,6-tetrahydropyrimidine

A sample of 180 grams of2-phenyl-4.4.6-trimethyl-2,3,4,5-tetrahydropyrimidine was distilledunder diminished pressure over 10 grams of potassium hydroxide. Thefraction 69 grams of b₀.8 = 123°-150° C., which solidified during thedistillation, as collected. Crystallization yielded2-phenyl-4.4.6-trimethyl-3,4,5,6-tetrahydropyrimidine as a white solid,m.p. 86°-87° C.; infrared spectrum 3.06 m μ weak (N--H) and 6.20 m μstrong (C═N), nuclear magnetic resonance spectrum, τ in ppm, solventCHCl₃, 2.28 multiplet 2H; 2.65 multiplet 3H; 4.93 singlet 1H; 6.61multiplet 1H; 8.42 multiplet 2H; 8.81 doublet 3H; 8.82 singlet 3H; and8.92 singlet 3H.

Anal. Calc.ed for C₁₃ H₁₈ N₂ : N, 13.86. Found: N, 13.6.

EXAMPLE 36 Glyoxal, mesityloxide, ammonia condensate

A sample of 98 grams of mesityloxide and 200 cc. of 28% ammoniumhydroxide was stirred for 3 hours. To the mixture was added 72.5 gramsof a 40% aq. glyoxal solution. The mixture was stirred for 1/2 hour atambient temperature and evaporated under diminished pressure. There wasisolated 65 grams of a red viscous liquid.

Anal. Calc.ed for (C₇ H₁₃ N₂)_(x) : N, 22.3. Found: N, 21.9.

EXAMPLE 37 2.4.6-Collidine

A sample of 54.8 grams of2.4.4.6-tetramethyl-2,3,4,5-tetrahydropyrimidine was heated for 23 hoursat reflux temperature, 168°-179° C. to yield 41.3 g. of a red liquid.

Anal. Calc.ed for C₈ H₁₁ N: N, 11.58. Found: N, 11.38.

Distillation of the product yielded 2.4.6 collidine, b₂₀ = 66°-68° C.identical spectral characteristic with authentic 2.4.6 collidine.

In a fashion as described in example 37, the following 6-substituted2.4-dimethylpyridines, collected in Table V were prepared fromsubstituted 4.4.6 trimethyl-2,3,4,5-tetrahydropyrimidines.

                  Table V                                                         ______________________________________                                             Starting  Re-     Reaction      Nitro-                                        mtl. prod-                                                                              action  Tempera-                                                                             6-Substi-                                                                            gen                                      Ex.  uct from  time    ture   tuent in                                                                             Calc. Anal.                              No.  Exam. No. hours   ° C.                                                                          Product                                                                              ed    Found                              ______________________________________                                        38   3         17      172-180                                                                              n-propyl                                                                             10.37 10.3                               39   4         21      180    n-hexyl                                                                              7.92  7.8                                40   5         18      180    isopentyl                                                                            8.58  8.3                                ______________________________________                                    

EXAMPLE 41 2-n-Propyl-3.5-diethyl pyridine

Into a mixture of 62.9 grams of2.4-di-n-propyl-5-ethyl-2,3,4,5-tetrahydropyrimidine, 4 grams ofammonium acetate and 4 grams of copper (II) acetate was introducedoxygen gas. Under continuous stirring and introduction of oxygen gas,the mixture was heated for 3 hours at 96°-128° C. The resulting reactionmixture was distilled under diminished pressure. The fraction b₂₀122°-126° was collected as 37.2 grams (67.8% of theory) of2-n-propyl-3.5-diethyl pyridine; nuclear magnetic resonance spectrum, nosolvent, τ in ppm 1.62 doublet 1H; 2.62 doublet 1H; 7.33 multiplet 6H;8.20 multiplet 2H; 8.82 triplet and 9.03 triplet 9H.

Anal. Calc.ed for C₁₂ H₁₉ N: N, 7.91. Found: N, 7.8.

The products of the above reactions where THP's are prepared aresummarized in the following table

                                      TABLE A                                     __________________________________________________________________________     ##STR11##                                                                    Ring                                                                          Position                                                                             6     5      4     4      2     2                                      __________________________________________________________________________       Subst.                                                                     Ex Group                                                                             R.sub.1                                                                             R.sub.2                                                                              R.sub.3                                                                             R.sub.4                                                                              R.sub.5                                                                             R.sub.6                                __________________________________________________________________________     1     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             CH.sub.3                                                                            CH.sub.3                                2     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     CH.sub.3                                3     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     n-C.sub.3 H.sub.7                       4     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     n-C.sub.6 H.sub.13                      5     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     i-C.sub.5 H.sub.11                      6     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub. 3                                                                            H     Phenyl                                  7     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     i-C.sub.7 H.sub.15                      8     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     n-C.sub.8 H.sub.17                      9     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             H     CH.sub.3                               10     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             CH.sub.3                                                                            CH.sub.3                               11     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             CH.sub.3                                                                            C.sub.2 H.sub.5                        12     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             (CH.sub.2).sub.5                             13     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                              ##STR12##                                   14     CH.sub.3                                                                            H      CH.sub.3                                                                            CH.sub.3                                                                             (CH.sub.2).sub.5                             15                                                                             15-   (CH.sub.2).sub.4                                                                           (CH.sub.2).sub.5                                                                           (CH.sub.2).sub.5                             23                                                                            24                                                                                    ##STR13##                                                                                  ##STR14##                                                                                  ##STR15##                                   26     (CH.sub.2).sub.4                                                                           (CH.sub.2).sub.5                                                                           (CH.sub.2).sub.5                              28-                                                                          34     CH.sub.3                                                                           H       CH.sub.3                                                                            CH.sub.3                                                                             CH.sub.3                                                                            CH.sub.3                               34A    H    C.sub.2 H.sub.5                                                                       H     n-C.sub.3 H.sub.7                                                                    H     n-C.sub.3 H.sub.7                      __________________________________________________________________________

The compositions of this invention are useful as corrosion inhibitors,insecticides, anti-oxidants, biocides including bacterocides,fungicides, etc.

The xanthates, besides being useful as a catalyst for the preparation ofthe tetrahydro pyrimidines of this invention, are also useful ascorrosion inhibitors, oxygen scavengers, biocides, insecticides, etc.

The compositions of this invention can be converted to a wide variety ofderivatives including salts, quaternaries, isomerized pyrimidines,pyridines, etc.

I claim:
 1. A process of preparing 2,3,4,5-tetrahydropyrimidines whichcomprises reacting at ambient temperatures and pressures a carbonylcompound from the group consisting of aldehydes and ketones with ammoniaor ammonium hydroxide in the presence of 0.1 to 2.0 mole percent, basedupon the reactants of carbon disulfide as a catalyst.
 2. The process ofclaim 1 wherein the reaction is carried out by mixing the reactants fora period of up to 18 hours.
 3. The process of claim 1 where both aketone and an aldehyde is reacted.
 4. The process of claim 3 where theketone is mesityl oxide and the aldehyde is formaldehyde.
 5. The processof claim 1 which comprises placing 3-methyl-cyclohexanone and carbondisulfide in a reactor, adding ammonia over a period of four hours, uponcompletion of the addition of the ammonia, stirring the mixture for aperiod of 18 hours and recovering the 2,3,4,5-tetrahydropyrimidine. 6.The process of preparing 2,3,4,5-tetrahydropyrimidines which comprisesreacting a ketone and a carbon disulfide adduct of a2,3,4,5-tetrahydropyrimidine with ammonia by mixing and stirring thereactants for a period of 70 hours.
 7. The process of claim 6 where theketone is acetone, the adduct is the carbon disulfide adduct of2,4-dipentamethylene-5,6-tetramethylene-2,3,4,5-tetrahydropyrimidine andthe product obtained is2,3,4,4,6-pentamethyl-2,3,4,5-tetrahydropyrimidine.
 8. The process ofclaim 1 where the carbonyl compound has the formula ##STR16## where R₁and R₂ are hydrogen, alkyl, aryl, cycloalkyl, alkaryl, aralkyl, orheterocyclic or the R groups may be joined in a cyclic configuration.